1. Field of the Invention
The present invention relates generally to an end mill having a drilling capability to drill a hole, as well as a peripheral-milling capability to cut a slot or groove. More particularly, the invention is concerned with such an end mill which has both peripheral-milling and drilling capabilities, and all cutting edges or blades of which consist of replaceable or disposable inserts.
2. Description of the Prior Art
In the art of cutting tools, there has been a remarkably increasing trend toward the utilization of replaceable or disposable (throw-away) cutting inserts or tips to provide cutting edges, blades, teeth or whatever is appropriate to represent cutting portions of the tools. In the past approach to utilizing such replaceable inserts, drills and end mills have been regarded as different kinds of tools, and consequently treated independently of each other in different ways in an effort to use the inserts. This difference is based on the traditional recognition of incompatibility between the drills and the end mills in arrangement of the replaceble inserts. Accordingly, a slot-cutting operation has required an end mill, while a drilling operation has required a drill, a cutting tool which has been considered distinct from the end mill.
Nevertheless, there has been available a cutting tool which is able to perform both drilling and peripheral-milling cuts, but only within a limited range of a cutting depth of a hole or slot, that is, to a maximum depth of 10 mm or so which is equivalent to a size of the inserts to be used on the tool.
However, a cutting tool with such limited drilling and peripheral-milling capabilities is difficult to attain its dual functions when a hole or slot to be cut has a depth greater than a size of the inserts. No such tools have been known yet in the art.
Therefore, for a machining cycle including combined deep-hole drilling and deep-slot milling cuts (for example, in making dies), tools must be changed from one tool to another each time the machining operation is changed from a drilling cut to an end-milling cut, or vice versa. Alternatively, a workpiece involving such a machining cycle must be transferred through plural machines or machining stations which are exclusively designed to achieve different specific cutting steps. These machining methods are disadvantageous due to a low machining efficiency and a high cost of machining equipment.